Method and system to detect tampering using light detector

ABSTRACT

An optical anti-tamper system that includes at least one array of light sources located within a chassis and at least one array of photosensitive elements located within the chassis. The array of photosensitive elements are in communication with an alarm. The alarm is operable to transmit a tamper-event warning signal if an increased light level is detected by at least one array of photosensitive elements.

GOVERNMENT LICENSE RIGHTS

The U.S. Government may have certain rights in the present invention asprovided for by the terms of Government Contract #FA8650-04-C-8011awarded by the United States Air Force

This application is related to an application having an Ser. No.11/325,733, filed on the same date herewith. The H0010161-5809application is herein incorporated by reference.

BACKGROUND

The board layout and assorted microchips which comprise electrical andelectro-optical systems within boxes or chassis often includeproprietary circuit designs, source code, or encryption codes which needto be protected from reverse engineering or tampering. In order toprotect the proprietary circuits from tampering, the board and chipmanufacturers use various technologies including sealing the chips in anopaque or tamper resistant material, installing proprietary encryptioncode, or adding limited chassis or cover protection which could includesecurity seals, or mechanical cut-off switches. However, over the lastdecade, these technologies, and anti-tamper coatings are not effectiveagainst more intrusive technologies and advanced software tools used byreverse engineers to determine how a particular board or device works orhack into the software or software codes. For example, reverse engineersdrill small holes in the chassis and insert endoscope probes to view theproprietary contents of the chassis. They can also shine X-rays onindividual die to find which cells are “OFF” while others are “ON.” Thisprovides a decoding mechanism for the reverse engineer.

If the information that a reverse engineer obtains by reverseengineering proprietary boards and/or chips is related to advancedmilitary applications, the information leak may endanger nationalsecurity. In particular if the military is not aware of the leak,confidential information could become available to the reverse engineerin the future, without the military knowing that their information iscompromised. Additionally, the reverse engineer may be able invent waysto overcome the proprietary technology yielding the technologyineffective for its intended use.

If the information that a reverse engineer obtains by reverseengineering proprietary boards and/or chips is related to commercialapplications, the information leak could be used to undermine theeconomic security of the commercial vendor. If a commercial vendor isunaware of the transgression on their proprietary information, they areunable to take steps to impose a penalty or to obtain financialrestitution.

For the reasons stated above and for other reasons stated below whichwill become apparent to those skilled in the art upon reading andunderstanding the specification, there is a need in the art forprotecting proprietary boards and chips and for alerting a vendor orcustomer if the proprietary information is breached. In some cases inorder to keep the proprietary information away from reverse engineers,it is desirable to destroy the proprietary boards and chips if atampering event occurs.

SUMMARY

The embodiments of the present invention provide methods and systems foran optical anti-tamper system and will be understood by reading andstudying the following specification.

One aspect of the present invention provides an optical anti-tampersystem that includes at least one array of light sources located withina chassis and at least one array of photosensitive elements locatedwithin the chassis. The array of photosensitive elements is incommunication with an alarm. The alarm is operable to transmit atamper-event warning signal if an increased light level is detected byat least one array of photosensitive elements.

Another aspect of the present invention provides a method ofmanufacture. The method includes positioning at least one array of lightsources within a chassis, positioning at least one array ofphotosensitive elements within the chassis operable to receive lightfrom at least one array of light sources, positioning at least oneopaque layer to prevent light from propagating from the array of lightsources to any one of the arrays of photosensitive elements andconnecting an alarm in communication with one or more photosensitiveelements correlated to the array of photosensitive elements.

Yet another aspect of the present invention provides an opticalanti-tamper system that includes means to break an opaque layerpositioned over an array of light sources responsive to a touching ofone or more components within a chassis, means for detecting anincreased light level at an array of photosensitive elements within thechassis responsive to the break and means for generating a tamper-eventwarning signal responsive to the detecting.

Yet another aspect of the present invention provides a method to detecta tampering event. The method includes breaking an opaque layer in whichthe break is located between an array of light sources and one or morearrays of photosensitive elements within the chassis. The method furtherincludes transmitting light from a portion of the array of light sourcesthrough the opaque layer responsive to breaking the opaque layer,detecting an increase in a light level at the one or more array ofphotosensitive elements responsive to the transmitting light andgenerating a tamper-event warning signal responsive to the detecting.

DRAWINGS

Embodiments of the present invention can be more easily understood andfurther advantages and uses thereof more readily apparent, whenconsidered in view of the description of the preferred embodiments andthe following figures.

FIG. 1A is a top-view of an embodiment of a light emitting layeroptically coupled to a light source.

FIG. 1B is a top-view of an embodiment of a light detecting layeroptically coupled to a light detector.

FIG. 2 is an enlarged view of an uncoated emitter optical fiber.

FIG. 3 is an enlarged view of an emitter optical fiber in the lightemitting layer of FIG. 1A positioned adjacent to an a detector opticalfiber in the light detecting layer of FIG. 1B in accordance with anembodiment of the present invention.

FIG. 4A is a top-view of an embodiment of the optical anti-tampersystem.

FIG. 4B is an enlarged cross-sectional view of side view of a portion ofthe optical anti-tamper system of FIG. 4A.

FIG. 5 is an enlarged view of an emitter optical fiber and a detectoroptical fiber of FIG. 3 in a broken state.

FIG. 6 is a top-view of an embodiment of the optical anti-tamper systemof FIGS. 4A and 4B in a broken state.

FIG. 7 is a top-view of an embodiment of the optical anti-tamper systemof FIGS. 4A and 4B in a broken state.

FIG. 8 is an enlarged cross-sectional side view of a portion of theoptical anti-tamper system of FIG. 7 in the broken state.

FIGS. 9A and 9B show an alternative implementation for the lightemitting layer and light detecting layer of the present invention.

FIG. 10 is a top-view of another embodiment of the optical anti-tampersystem of the present invention.

FIG. 11 is an expanded cross-sectional side view of the opaque layerinterleaved between adjacent the emitter optical fibers and the detectoroptical fiber in accordance with an embodiment of the present invention.

FIGS. 12A and 12B are cross-sectional side views of a portion of theoptical anti-tamper system of FIG. 11 in an unbroken state.

FIGS. 13A and 13B are cross-sectional side views of the portion of theoptical anti-tamper system of FIG. 11 in a broken state.

FIG. 14 is a side view of an embodiment of the optical anti-tampersystem of the present invention.

FIG. 15 is a side-view of an embodiment of the optical anti-tampersystem of FIG. 14 in a broken state.

FIG. 16 is a side-view of an embodiment of the optical anti-tampersystem of FIG. 14 in a broken state.

FIG. 17 is an embodiment of a method to detect a tampering event of acomponent within a chassis of the present invention.

FIG. 18 is an embodiment of a method to manufacture an opticalanti-tamper system of the present invention.

FIG. 19A is a top-view of an embodiment of the optical anti-tampersystem.

FIG. 19B is the optical anti-tamper system of FIG. 19A in a brokenstate.

FIG. 19C is an enlarged view of the cut area.

In accordance with common practice, the various described features arenot drawn to scale but are drawn to emphasize features relevant to thepresent invention. Reference characters denote like elements throughoutfigures and text.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings that form a part hereof, and in which is shown byway of illustration specific illustrative embodiments in which theinvention may be practiced. These embodiments are described insufficient detail to enable those skilled in the art to practice theinvention, and it is to be understood that other embodiments may beutilized and that logical, mechanical and electrical changes may be madewithout departing from the scope of the present invention. The followingdetailed description is, therefore, not to be taken in a limiting sense.

Various implementations of embodiments of optical anti-tamper systemsare described herein. Each of the described optical anti-tamper systemsis located within a chassis and includes a light emitting layer and alight detecting layer positioned within a line of sight with each other.During a tampering event, one or more detectors in communication withthe light detecting layer detect an increase in light level as a resultof the tampering. An alarm in communication with the detector transmitsa tamper-event warning signal in response to the increased light levelat the detector.

A tampering event, as defined herein, occurs when a component to beprotected is viewed and/or touched by a person or an object. Achassis-opening tampering event, occurs when a person opens a chassis,in which the protected component is enclosed, in order to analyze thecomponent. An opaque-layer-break tampering event occurs when a person orobject touches or probes the protected component in order to analyze thecomponent. FIGS. 1-4 and 6-9 illustrate views (or partial views) ofimplementations of embodiments of an optical anti-tamper system thatinclude optical fibers.

FIG. 1A is a top-view of an embodiment of a light emitting layer 100optically coupled to a light source 150. The light emitting layer 100includes a plurality of emitter optical fibers designated generally as105. As shown in FIG. 1A, the input ends generally designated as 115 ofthe emitter optical fibers 105 are bundled for optical coupling to oneor more light sources represented as a single light source 150. In thismanner, one or more light sources 150 are optically coupled to the lightemitting layer 100. The output ends generally designated as 117 of theemitter optical fibers 105 are spatially separated by the distance D1.

A main body region generally designated as 107 of each of the emitteroptical fibers 105 lies in a straight line. The main body regions 107 ofneighboring emitter optical fibers 105 are separated by approximatelyequal distances D1. The main body region 107 ends at the output ends 117of the emitter optical fiber 105. In one implementation of theembodiment of emitter optical fiber 105, the main body region 107 isabout half the length of the emitter optical fiber 105. In anotherimplementation of the embodiment of emitter optical fibers105, the mainbody regions 107 range from between half the length of the respectiveemitter optical fiber 105 and three-quarters of the length of therespective emitter optical fiber 105. The main body regions 107 ofemitter optical fibers 105 lie approximately in a plane defined byvectors X and Y. Additional physical details of embodiments of theemitter optical fibers 105 are described below with reference to FIGS. 2and 3.

FIG. 1B is a top-view of an embodiment of a light detecting layer 200optically coupled to a light detector 160. The light detecting layer 200includes a plurality of detector optical fibers generally designated as106. As shown in FIG. 1B, the output ends generally designated as 125 ofthe of detector optical fibers 106 are bundled for optical coupling toone or more light detectors represented as a single light detector 160.In this manner, one or more light detectors 160 are optically coupled tothe light detecting layer 200 so that the light detector 160 isoptically coupled to receive light that propagates through any of thedetector optical fibers 106. The input ends generally designated as 127of the of detector optical fibers 106 are spatially separated by thedistance D2.

A main body region 108 of each of the detector optical fibers 106 liesin a straight line. The main body regions 108 of neighboring detectoroptical fibers 106 are separated by approximately equal distances D2.The main body region 108 ends at the input ends 127 of the detectoroptical fiber 106. In one implementation of the embodiment of detectoroptical fiber 106, the main body region 108 is about half the length ofthe detector optical fiber 106. In another implementation of theembodiment of detector optical fiber 106, the main body region 108ranges from between half the length of the respective detector opticalfiber 106 and three-quarters of the length of the respective detectoroptical fiber 106.

The main body regions 108 of detector optical fibers 106 lieapproximately in the plane defined by vectors X and Y. Additionalphysical details of embodiments of the detector optical fibers 106 aredescribed below with reference to FIG. 3. In one implementation ofembodiments of light emitting layer 100 and light detecting layer 200,the distance D1 is about 1.5 to 3 times the diameter of the detectoroptical fiber 106 and the distance D2 is about 1.5 to 3 times thediameter of the emitter optical fiber 105. In another implementation ofembodiments of light emitting layer 100 and light detecting layer 200,the distance D1 is about equal to the distance D2.

FIG. 2 is an enlarged view of an uncoated emitter optical fiber 104. Inan embodiment of the present invention illustrated in FIGS. 10-13, aplurality of uncoated emitter optical fibers 104 form the light emittinglayer 100. The emitter optical fiber 105 is formed by coating at leastthe bevel cuts 190 of the uncoated emitter optical fibers 104 with athin film opaque layer. In the embodiment of the present inventionillustrated in FIGS. 3-8, the emitter optical fibers 105 form the lightemitting layer 100.

As shown in FIG. 2, the input end 115 of an emitter optical fiber 104receives light emitted from the light source 150. The emitted light 302diverges from the light source 150 into more than one direction ofpropagation. The emitted light 302 is coupled into the core 170 of theemitter optical fiber 104 at the input end 115. The side surface 90 ofthe emitter optical fiber 104 is the outer surface of the cladding 180of emitter optical fiber 104. The side surface 90 has bevel cuts 190that extend through the cladding 180 and into the core 170 of theemitter optical fiber 104. A portion of the light 310 propagatingthrough the emitter optical fiber 104 is incident on a bevel cut 190 andis propagated outside the emitter optical fiber 104 as light 300. Inthis manner, the bevel cuts 190 operate as output ports on a sidesurface of an emitter light pipe, since the bevel cuts 190 are operableto transmit light 310 propagating through the emitter optical fiber 104outside the side surface 90 of the emitter optical fiber 104.

FIG. 3 is an enlarged view of an emitter optical fiber 105 in the lightemitting layer 100 of FIG. 1A positioned adjacent to an a detectoroptical fiber 206 in the light detecting layer 200 of FIG. 1B inaccordance with an embodiment of the present invention. The emitteroptical fiber 105 is the emitter optical fiber 104 of FIG. 2 at leastpartially covered with a thin film opaque layer 240.

The main body region 107 of an emitter optical fiber 105 is shownadjacent to the main body region 108 of a detector optical fiber 106. Asshown in FIG. 3, the emitter optical fiber 105 has a thin film opaquelayer 240 covering at least the bevel cuts 190 and also a portion of theside surface 90 for the emitter optical fiber 105. As in FIG. 2, thelight 310 is propagating in the core 170 of the emitter optical fiber105. The thin film opaque layer 240 that coats the bevel cut 190 isdesigned to absorb, scatter and/or reflect the one or more wavelengthsof the light 310 that propagate in the emitter optical fibers 105 andthe detector optical fibers 106. In this manner, the thin film opaquelayer 240 prevents the light 310 that is propagating through the emitteroptical fiber 105 from being transmitted outside the side surface 90 ofthe emitter optical fiber 105. The terms “opaque layer” and “thin filmopaque layer” are used interchangeably throughout this document.

The side surface 80 of the detector optical fiber 106 is the outersurface of the cladding 280 of the detector optical fiber 106. The sidesurface 80 has bevel cuts 290 that extend through the cladding 280 andinto the core 270 of the detector optical fiber 106. There is not a thinfilm opaque layer 240 covering the bevel cuts 290 or the side surface 80for the detector optical fiber 106.

A transparent abrasive layer 275 includes a gel 250 and abrasiveparticles 260 dispersed within the gel 250. The transparent abrasivelayer 275 is located at the interface between the emitter optical fiber105 and the detector optical fiber 106. The gel 250 is viscous and thetransparent abrasive particles 260 are solid particles with one or moresharp edges. In one implementation of this embodiment, the transparentabrasive layer is replaced with a transparent layer that does notinclude abrasive particles 260.

Also shown in FIG. 3 is a top reflective surface 70 and a bottomreflective surface 71. The top reflective surface 70 and a bottomreflective surface 71 surround the emitter optical fiber 105 and thedetector optical fiber 106.

This relative positioning of the emitter optical fiber 105 covered atleast in the bevel cuts 190 by the thin film opaque layer 24, thedetector optical fiber 106 with bevel cuts 290, gel 250 filled with theabrasive particles 260 all surrounded by the top reflective surface 70and the bottom reflective surface 71 make the emitter optical fiber 105and the detector optical fiber 106 suitable for operation in anembodiment of an optical anti-tamper system 12 (FIG. 4).

FIG. 4A is a top-view of an embodiment of the optical anti-tamper system12. The plane upon which the cross-section view of FIG. 4B is taken isindicated by section line 4B-4B in FIG. 4A. FIG. 4B is an enlarged viewof side view of a portion of the optical anti-tamper system 12 of FIG.4A. The optical anti-tamper system 12 includes the light emitting layer100, the light detecting layer 200, the transparent abrasive layer 275,light source 150, light detector 160, the top reflective surface 70 (notvisible from this cross-sectional top-view), the bottom reflectivesurface 71 and an alarm 305 enclosed within a chassis 310 and in contactwith a proprietary part of component 45 that is to be protected from atampering event. The emitter optical fibers 105 of light emitting layer100 are interleaved with the detector optical fiber 106 of the lightdetecting layer 200. The optical anti-tamper system 12 operates todetect a tampering event. When an object or persons touches theinterleaved light emitting layer 100 and light detecting layer 200 as itoverlies at least a portion of the component 45 the thin film opaquelayer 24 breaks in an opaque-layer-break tampering event.

As described above with reference FIG. 1A, the emitter optical fibers105 are optically coupled at input ends 115 to receive light 302 emittedfrom the light source 150. As described above with reference to FIG. 1B,the light detector 160 is optically coupled to receive any lightpropagating in the detector optical fiber 106. The emitter optical fiber105, including the bevel cuts 190 covered by the thin film opaque layer24, the detector optical fiber 106 with bevel cuts 290, gel 250 filledwith the abrasive particles 260 are positioned as described above withreference to FIG. 3. In this embodiment, the bottom reflective surface71 lies adjacent to and below the light emitting layer 100 and the lightdetecting layer 200 while the top reflective surface 70 (FIG. 4B) liesadjacent to and above the light emitting layer 100 and the lightdetecting layer 200. Top reflective surface 70 and bottom reflectivesurface 71 lie in a plane parallel to the plane defined by the vectors Xand Y. The bottom reflective surface 71 overlies the bottom surface 312of the chassis 310.

The detector 160 is in communication with alarm 305 as indicated byarrow 175 (FIG. 4A). The alarm 305 is operable to transmit atamper-event warning signal to an external system 350 if an increasedlight level is detected by detector 160. The external system 350 isexternal to the chassis 310 (FIG. 4A). The component 45, shown in FIGS.4A and 4B as one component, is representative of one or more components.The portion of the component 45 covered by the light emitting layer 100and the light detecting layer 200 includes the proprietary technology.

In one implementation of an embodiment of the optical anti-tamper system12, the light source 150 includes more than one light source. In anotherimplementation of an embodiment of the optical anti-tamper system 12,the light source 150 includes a plurality of light sources emitting atmore than one wavelength. In yet another implementation an embodiment ofthe optical anti-tamper system 12, the light source 150 is opticallycoupled to the emitter optical fibers 105 with an optical lens system.The light source 150 can be light emitting diodes, edge emitting laserdiodes, vertical cavity surface emitting diodes, gas lasers, or otherlight source capable of coupling to the light emitting layer 100.

In one implementation of the embodiments of the light detecting layer200, the light detector 160 is operable to detect low levels of light.The light detector 160 does not need to detect light at high data ratesand thus, is not required to be a high speed detector. Therefore, lightdetector 160 is relatively inexpensive slow detector and/or large areadetector. The light detector 160 is operable to detect visible light. Inone implementation of this embodiment of the light detecting layer 200,the light detector 160 senses wavelengths in one or more of the infraredspectral range, the red spectral range, the blue-green spectral rangeand the ultra-violet spectral range. In another implementation of thisembodiment of the light detecting layer 200, the light detector 160 is aplurality of light sensors and each light detector senses a differentrange of wavelengths. In yet another implementation of this embodiment,the light detector 160 includes a first plurality of light detectorsthat sense a first range of wavelengths and a second plurality of lightdetectors that sense a second range of wavelengths.

The emitter optical fibers 105 and detector optical fibers 106 can beglass optical fiber, plastic optical fibers, multimode optical fiber,single mode optical fiber, and any flexible light pipe. For a givenapplication and/or customer, the selection of optical fiber type and theoptical fiber form can be optimized to meet the durability requirements,anti-tamper requirements, and cost requirements for specific components45 being protected. The phrase “optical fiber” and “light pipe” are usedinterchangeably throughout this document.

The alarm 305 includes circuits, such as digital IC or analog IC, thatare operable to perform the functions of the alarm 305 as describedbelow with reference to method 1700 of FIG. 17. In one implementation ofthe optical anti-tamper system 12, the alarm 305 includes a processoroperable to execute software and/or firmware that causes the processorto perform at least some of the processing described here as beingperformed by the optical anti-tamper system 12. At least a portion ofsuch software and/or firmware executed by the processor and any relateddata structures are stored in memory during execution. In oneimplementation of the optical anti-tamper system 12, the alarm 305includes a processor and a memory, which comprises any suitable memorynow known or later developed such as, for example, random access memory(RAM), read only memory (ROM), and/or registers within the processor.

In one implementation of this embodiment of the optical anti-tampersystem 12, the light detector 160 is fixed to a surface of a boardlocated in the chassis 310. In another implementation of this embodimentof the optical anti-tamper system 12, the top reflective surface 70 andthe bottom reflective surface 71 are not included. In yet anotherimplementation of this embodiment of the optical anti-tamper system 12,the components 45 include an electronic circuit board.

FIG. 3 shows an emitter optical fiber 105 and detector optical fiber 106in an unbroken state in which the thin film opaque layer 240 isunbroken. FIG. 4A is a cross-sectional top-view of the opticalanti-tamper system 12 in an unbroken state and no light from the emitteroptical fiber 105 is transmitted to the detector optical fiber 106. Whenthe optical anti-tamper system 12 is touched by a person or an object,the thin film opaque layer 240 is broken by the abrasive particles 260in the transparent abrasive layer 275 and light 310 from the emitteroptical fiber 105 is transmitted to the detector optical fiber 106 asdescribed below with reference to method 1700 of FIG. 17.

FIG. 5 is an enlarged view of an emitter optical fiber 105 and detectoroptical fiber 106 of FIG. 3 in a broken state. The emitter optical fiber105 and detector optical fiber 106 are in a broken state after thetransparent abrasive particles 260 are pushed against the thin filmopaque layer 240 in the bevel cut 190 and break the thin film opaquelayer 240. FIG. 6 is a top-view of an embodiment of the opticalanti-tamper system 12 of FIGS. 4A and 4B in a broken state. In FIG. 6,the optical anti-tamper system 12 is in the process of transmitting atamper-event warning signal 360. Light 300 that passed through the breakin the thin film opaque layer 240 was coupled into the core 270 and anincreased level of light was detected at the light detector 160. In FIG.6, a radio frequency tamper-event warning signal 360 is beingtransmitted to an external system 350. As shown in FIG. 6, light 300 iscoupled from the detector optical fibers 106 to the light detector 160.The light level incident on the light detector 160 is now greater thanthe light level incident on the light detector 160 during thecalibration process described above with reference to block 1702 of FIG.17.

FIG. 7 is a top-view of an embodiment of the optical anti-tamper systemin a broken state. In FIG. 7, the alarm 500 replaces the alarm 350 andthe proprietary components 45 are being damaged by material 135 thatcontacts the components 45 in response to a tampering event. FIG. 8 isan enlarged cross-sectional side view of a portion of an embodiment ofthe optical anti-tamper system of FIG. 7 in the broken state. FIG. 8shows the viscous transparent abrasive layer 275 as the thin topreflective layer 70 overlaying the transparent abrasive layer 275 ispushed downward in the touched area 400. This push moves the emitteroptical fiber 105 and the detector optical fiber 206 within thetransparent abrasive layer 275 so that transparent abrasive particles260 are forced into contact with the emitter optical fiber 105 and breakthe thin film opaque layer 240.

FIGS. 9A and 9B show an alternative implementation for the lightemitting layer 100 and light detecting layer 200. The emitter opticalfiber 105 and the detector optical fiber 106 are woven rather thaninterleaved. FIG. 9A shows a top-view of the light emitting layer 100and light detecting layer 200 optically coupled to the light source 150and the light detector 160, respectively. The plane upon which thecross-section view of FIG. 9B is taken is indicated by section line9B-9B in FIG. 9A. In FIG. 9B, the emitter optical fiber 105A (FIG. 9A)is shown in cross-section with the four detector optical fibers106A-106D alternately below and above the emitter optical fiber 105A. Asis understood about weaving patterns, a cross-sectional view of emitteroptical fiber 105B (FIG. 9A) is FIG. 9B flipped about the horizontalline C-C′. In an embodiment of an optical anti-tamper system thatimplements a light emitting layer 100 woven with the light detectinglayer 200, the transparent abrasive layer 275, as described above withreference to FIG. 3, surrounds the light emitting layer 100 and lightdetecting layer 200. The woven light emitting layer 100 and lightdetecting layer 200 are located above and/or near the components 45 tobe protected from a tamper-event. During a tamper event, the woven lightemitting layer 100 and light detecting layer 200 are touched, the thinfilm opaque layer 240 in the bevel cuts 190 is broken and the lightdetector 160 receives light 300.

FIGS. 10-13 illustrate views (or partial views) of implementations ofanother embodiment of an optical anti-tamper system 12. The manner oflocating an opaque layer between the light emitting layer 100 and thelight detecting layer 200 to prevent light emitted from the lightemitting layer 100 from being incident on the light detecting layer 200when in an unbroken state differs in this implementation. Thisembodiment does not include a thin film opaque layer 240 covering theemitter optical fiber.

FIG. 10 is a top-view of an embodiment of the optical anti-tamper system13. Optical anti-tamper system 13 is similar to optical anti-tampersystem 12 except the bevel cuts 190 are not coated with the thin filmopaque layer 240. The emitter optical fiber 104 is uncoated asillustrated in FIG. 2. Between each adjacent emitter optical fiber 104and the detector optical fiber 106 there is an opaque layer 430. Thetransparent abrasive layer 275 contacts the opaque layer 430. In oneimplementation of this embodiment, the transparent abrasive layer 275 isreplaced with a transparent layer that does not include abrasiveparticles.

FIG. 11 is an expanded cross-sectional side view of the opaque layer 430interleaved between adjacent the emitter optical fibers 104 and thedetector optical fiber 106 in accordance with an embodiment of thepresent invention. The plane upon which the cross-section view of FIG.12 is taken is indicated by section line 12-12 in FIG. 11. The opaquelayers 430 are comb-like structures protruding from a base 425. Theopaque layers 430 extend at least the length of the main body region 107of the emitter optical fiber 104, which is parallel to and about thelength of the main body region 108 of detector optical fiber 106. Theopaque layers 430 extend in height from the base 425 to about thediameter of the emitter optical fiber 104 and detector optical fiber106.

There is an opaque layer 430 between each adjacent emitter optical fiber104 and detector optical fiber 106. The transparent abrasive layer 275fills in the space between the emitter optical fiber 104 and the opaquelayer 430 and between the detector optical fiber 106 and the opaquelayer 430. The transparent abrasive layer 275 includes the gel 250 andthe transparent abrasive particles 260 as described above with referenceto FIG. 3. The base 425 overlies the one or more components 45. In oneimplementation of this embodiment the base 425 is reflective. In anotherimplementation of this embodiment, the base 425 and the opaque layer 430are the same material. In one case, the base 425 and the opaque layer430 are molded from an opaque material. In another case, the base 425and the opaque layer 430 are formed using processing techniques to formthe comb like structure.

FIGS. 12A and 12B are cross-sectional side views of a portion of theoptical anti-tamper system of FIG. 11 in an unbroken state. FIG. 12A isa cross-sectional side view of a portion of the optical anti-tampersystem of FIG. 11 in an unbroken state. Region 432 of FIG. 12A is shownin an enlarged view in FIG. 12B. As shown in FIG. 12B, the transparentabrasive particles 260 are in contact or near contact with the opaquelayer 430. A top reflective surface 70 overlies adjacent emitter opticalfiber 104 and detector optical fiber 106. The top reflective surface 70and the base 425 form an envelope to hold the gel 250 and thetransparent abrasive particles 260 in the space between the emitteroptical fiber 104 and the opaque layer 430 and between the detectoroptical fiber 106 and the opaque layer 430. Light 310 is emitted fromthe bevel cut 190 and is absorbed by the opaque layer 430. In FIGS. 12Aand 12B, the opaque layer 430 is unbroken since the transparent abrasiveparticles 260 are not forced into the opaque layer 430.

FIGS. 13A and 13B are cross-sectional side views of the portion of theoptical anti-tamper system of FIG. 11 in a broken state. FIG. 13A is aside view of the portion of the optical anti-tamper system of FIGS. 12Aand 13B in a broken state after a tampering event has occurred. Region434 of FIG. 13A is shown in an enlarged view in FIG. 13B. As shown inFIG. 13B, the opaque layer 430 is broken. During a tampering event thetop reflective surface 70 or base 425 is touched so that transparentabrasive particles 260 are forced into contact with the opaque layer 430and the opaque layer 430 ruptures. The light 300 is emitted from thebevel cut 190 in emitter optical fiber 104 and coupled into the core 280of the detector optical fiber 106 via the bevel cut 290. The break inopaque layer 430 is along a line of sight between the adjacent emitteroptical fiber 104 and detector optical fiber 106. In this manner thelight 300 is coupled into the detector optical fiber 106 and istransmitted to the detector 160. Light in the detector optical fiber 106is coupled into the light detector 160. The light detector 160 detectsan increase in the light level from the calibrated light level inresponse to the light 300 being transmitted to the core 270 of thedetector optical fiber 106.

FIGS. 14-16 illustrate views (or partial views) of implementations anoptical anti-tamper system 14. In this embodiment, the light emittinglayer is an array of light sources 450 and the light detecting layer isan array of photosensitive elements 163. In optical anti-tamper system14 an opaque layer is located between the array of light sources and thearray of photosensitive elements. The opaque layer prevents lightemitted from the array of light sources from being incident on the arrayof photosensitive elements when in an unbroken state. A transparentabrasive layer is located between the array of light sources and thearray of photosensitive elements. The transparent abrasive layer breaksthe opaque layer when a protected component positioned adjacent to thetransparent abrasive layer is touched during a tampering event puttingthe opaque layer in a broken state. The array of light sources and thearray of photosensitive elements are positioned so that the lightemitted from the array of light sources is incident on the array ofphotosensitive elements when the opaque layer is in the broken state.

In one implementation of this embodiment, the array of light sources 450is selected from the group comprising an array of light emitting diodes,an array of lasers, an array of vertical cavity light emitting diodesand combinations thereof. In another one implementation of thisembodiment, the array of photosensitive elements 163 is selected from anarray of photosensitive pixels, a charge-coupled device, an array ofphoto-detectors and combinations thereof. In yet another oneimplementation of this embodiment, the array of photosensitive elements163 is replaced by a single light detector such as light detector 160.In yet another one implementation of this embodiment, the array ofphotosensitive elements is replaced by a single light detector 160 andan array of photosensitive elements 163 as shown in FIG. 14.

FIG. 14 is a side view of an embodiment of the optical anti-tampersystem 14. The opaque layer 240 is designed to absorb the light emittedfrom the array of light sources 450. The opaque layer 240 completelyoverlies the array of light sources 450. The transparent abrasive layer275 overlies, at least in part, the opaque layer 240. The protectedcomponents 45 are located over the transparent abrasive layer 275. Inone implementation of the embodiment of optical anti-tamper system 14,the photosensitive elements include a light detector 161 and an array ofphotosensitive elements 163. In another implementation of thisembodiment, the transparent abrasive layer is replaced with atransparent layer that does not include abrasive particles 260.

FIG. 15 is a side-view of an embodiment of the optical anti-tampersystem 14 of FIG. 14 in a broken state. In FIG. 15, the opticalanti-tamper system 14 is in the process of transmitting a tamper-eventwarning signal 360 to the external system as described above withreference to FIG. 6. The array of photosensitive elements 163 of theoptical anti-tamper system 14 are calibrated for the ambient light levelin the closed chassis 310. During a tampering event the transparentabrasive layer 275 is contacted and the opaque layer 240 is broken bythe transparent abrasive particles 260 in the transparent abrasive layer275.

The light detector 161 and the array of photosensitive elements 163 arealong a line of sight with the array of light sources 450 so that thebreak in the opaque layer 240 in the touched area 400 allows light fromthe array of light sources 450 to be incident on the light detector 161and the array of photosensitive elements 163. The light detector 161 andthe array of photosensitive elements 163 are in communication with alarm305 as indicated by arrows 175. The light level of the light incident onlight detector 161 and the array of photosensitive elements 163increases when the opaque layer 240 is broken. The alarm 305 is operableto transmit a tamper-event warning signal to an external system 350 ifan increased light level is detected by light detector 161 and the arrayof photosensitive elements 163. The external system 350 is external tothe chassis 310. The component 45, shown in FIGS. 14-16, as onecomponent, is representative of one or more components. The portion ofthe component 45 covered by the light emitting layer 100 and the lightdetecting layer 200 includes the proprietary technology.

FIG. 16 is a side-view of an embodiment of the optical anti-tampersystem of FIG. 14 in a broken state. As shown in FIG. 16, the alarm 500includes a container 570. When the alarm 500 generates a tamper-eventwarning signal, the container 570 is automatically triggered by thealarm 500 to open. When the container 570 opens, a material 135 in thecontainer is emitted and disperses within the open chassis 40. Thematerial 135 is the same material described above with reference toFIGS. 7 and 8 and is operable to destroy or damage at least a portion ofthe components 45 that are being protected to prevent proprietaryinformation from being retrieved from the components 45 in the openchassis 40.

In this manner, optical anti-tamper system 14 and all theimplementations of the embodiments described herein are operable tobreak an opaque layer responsive to a touching of one or more componentswithin a chassis, to detect an increased light level within the chassisresponsive to the break and to generate tamper-event warning signalresponsive to the detecting.

If the event that the chassis 310 is opened in an environment thatincludes externally generated light, the array of photosensitiveelements 163 of the optical anti-tamper system 14 experience an increasein detected light level and the alarm 305 or 500 generate a tamper-eventwarning signal.

FIG. 17 is a method 1700 to detect a tampering event of a component 45within a chassis 310 in one embodiment of the present invention. Themethod 1700 is described with reference to the optical anti-tampersystem 14 as illustrated in FIGS. 14 and 15. The alarm 305 has stored incomputer readable medium at least one computer program includingcomputer readable code to perform the operations described withreference to method 1700.

The one or more arrays of photosensitive elements 163 of the opticalanti-tamper system 14 are calibrated for the ambient light level in theclosed chassis 310 (block 1702). The optical anti-tamper system 14 ispositioned as shown in FIGS. 14 and 15. The chassis 310 is sealed toprevent any light external to the chassis 310 from entering the chassis310. There may be one or more light sources within the chassis 310 fornormal operation of the components 45. In one implementation of theexemplary optical anti-tamper system 14 of FIGS. 14 and 15, thecomponents 45 include light emitting diodes. Once the chassis 310 isclosed, the alarm 305 is triggered to receive signals from the array ofphotosensitive elements 163. The signals indicate a light level in thechassis 310 that is the calibrated light level. In anotherimplementation of the exemplary optical anti-tamper system 14 of FIGS.14 and 15, a processor external to the alarm 305 triggers the alarm 305to calibrate the optical anti-tamper system 14.

At block 1704, a touch on the optical anti-tamper system 14 breaks thethin film opaque layer 240 (in one or more places) in response to atampering event. The break in thin film opaque layer 240 is positionedbetween the array of light sources 450 and the array of photosensitiveelements 163 within the chassis 310. When the optical anti-tamper system14 is touched, the transparent abrasive particles 260 (FIG. 3) arepushed through the viscous gel 250 (FIG. 3) against the thin film opaquelayer 240. The sharp edges of the transparent abrasive particle 260 cutand tear the thin film opaque layer 240 to break open the thin filmopaque layer 240. In one implementation of this embodiment, thetransparent abrasive particles 260 are not included in the transparentabrasive layer 275.

Light 300 is transmitted from a portion of the array of light sources450 through the thin film opaque layer 240 to the array ofphotosensitive elements 163 (block 1706). As shown in FIG. 15, light 300in a touched area 400 is propagating through the transparent abrasivelayer 275 from the emitter optical fibers 105 to the array ofphotosensitive elements 163.

The array of photosensitive elements 163 detects an increase in thelight level from the calibrated light level in response to the light 300being transmitted from a portion of the array of light sources 450through the thin film opaque layer 240 to the array of photosensitiveelements 163 (block 1708).

The alarm 305 receives the signal 175 indicative of the light incidenton the array of photosensitive elements 163. The circuitry within thealarm 305 is operable to retrieve the calibrated light level for thecalibrated array of photosensitive elements 163 and compare the valuesof the calibrated light level and the light level when light 130 isincident on the array of photosensitive elements 163. The alarm 305determines that there is an increased light level based on thecomparison. The alarm 305 generates a tamper-event warning signal 360responsive to the increased light level at array of photosensitiveelements 163 (block 1710). In this manner the, the alarm 305 generates atamper-event warning signal 30 in response to detecting the increasedlight level at array of photosensitive elements 163 that is correlatedto the light transmitted to the array of photosensitive elements 163.

In one implementation of the method 1700, after the alarm 305 generatesa tamper-event warning signal responsive to the detected increased lightlevel, the alarm 305 in the optical anti-tamper system 14 transmits thetamper-event warning signal 360 to an external system 350 (block 1712).As shown in FIG. 6, the tamper-event warning signal 360 is transmittedas a radio frequency signal 360 to the external system 350. In oneimplementation of this embodiment of block 1712 of method 1700, theradio frequency signal is generated by a transmitter. In anotherimplementation of this embodiment of block 1712 of method 1700, theradio frequency signal is generated by a transceiver in the alarm 305.

The term ‘tamper-event warning signal” as defined herein, includes oneor more output events operable to notify one or more systems or peoplethat the component 45 protected by an optical anti-tamper system 14 hasbeen touched. The output events that warn of a tampering event includean audio alert, a signal transmitted to an external system 350, and atrigger of a visual indicator at an external system 350.

In another implementation of the method 1700, the optical anti-tampersystem 14 damages at least a portion of the components 45 in the chassis310 (block 1714) when the alarm 305 generates a tamper-event warningsignal. In FIG. 16, the optical anti-tamper system 14 includes alarm 500and the optical anti-tamper system 14 is in the process of damaging atleast a portion of components 45 within the chassis 310 responsive tothe tamper-event warning signal. As defined herein, the term “damaging”refers to making the protected software and/or hardware inoperableand/or irretrievable.

As shown in FIG. 16, the alarm 500 includes a container 570. When thealarm 500 generates a tamper-event warning signal, the container 570 isautomatically triggered by the alarm 500 to open. When the container 570opens, a material 135 in the container is emitted and disperses withinthe open chassis 40. In FIG. 16, the material 135 is indicated as aplurality of circles to represent molecules or groups of molecules ofthe diffusing material 135. The material 135 is operable to destroy ordamage at least a portion of the components 45 that are being protectedto prevent proprietary information from being retrieved from thecomponents. In one implementation of this embodiment of block 1714 ofmethod 1700, the container 570 opens due to a mechanical switch thatoperates responsive to the trigger. In another implementation of thisembodiment of block 1714 of method 1700, the container 570 opens due toan electric and/or electro-optic switch that operates responsive to thetrigger.

In one implementation of this embodiment of block 1714 of method 1700,the material 135 is a caustic chemical that erodes conformal coatingsand the trace lines within and/or connecting components 45. The causticchemical can be in a gas or liquid state. In another implementation ofthis embodiment of block 1714 of method 1700, the components 45 arepowered to drive the signal lines and material 135 is a conductivesubstance that electrically shorts conductive trace lines and devicepins connecting and/or within the circuits of the components 45. In thisembodiment, the material 135 does not short the power and groundconnections of the component 45 powered to drive the signal lines whileshorting the output drivers of functional circuits within the components45. In yet another implementation of this embodiment of block 1714 ofmethod 1700, more than one material is emitted and dispersed within thechassis 40. In yet another implementation of this embodiment of block1714 of method 1700, more than one material is emitted and dispersedwithin the chassis 40 to form a third material 135 that damages ordestroys at least the proprietary components within the chassis 40.

In one implementation of an opaque-layer-break tampering event, arelative movement between two or more components within the chassis 310causes the two or more components 45 to touch each other. When the twocomponents 45 touch each other, the abrasive particles 260 in thetransparent abrasive layer 275 that overlie at least a section of theopaque layer 240 break at least a portion of the opaque layer 240. In anexemplary case, a plurality of boards in one chassis 310 hold protectedcomponents 45. If the chassis 310 is opened and a board is removed, theboard being removed can inadvertently the touching another board. When afirst board touches against an optical anti-tamper system 14 on a secondboard, the alarm 305 generates a tamper-event warning signal.

In this manner, optical anti-tamper system 14 and all theimplementations of the embodiments described herein are operable tobreak an opaque layer positioned over an array of light sourcesresponsive to a touching of one or more components within a chassis, todetect an increased light level within the chassis responsive to thebreak and to generate a tamper-event warning signal responsive to thedetecting.

In a closed state the chassis 310 is impenetrable to light. During achassis-opening tampering event, a person opens the chassis 310 in anarea with external ambient light from an external light source. Thelight enters the chassis 310 and the array of photosensitive elements163 detects an increase in light level. The light does not propagatethrough transparent abrasive layer 275 but is directly incident on thearray of photosensitive elements 163. The alarm 305 generates achassis-open-tamper-event warning signal responsive to the increasedlight level. If a person opens the chassis 310 in the dark, there is nochassis-open-tamper-event warning signal responsive to opening thechassis 310. However, if the person then touches the components 45, theopaque-layer-break tampering event generates anopaque-layer-break-tamper-event warning signal responsive to the touch.In this manner the optical anti-tamper system 14 and all theimplementations of the embodiments described herein provide two levelsof anti-tamper protection.

FIG. 18 is an embodiment of a method 1800 to manufacture an opticalanti-tamper system. The method of manufacture is described for opticalanti-tamper system 14 as shown in FIG. 16.

At block 1802, one or more array of light sources 450 is positionedwithin the chassis 310 along with the components 45 to be protected andthe alarm 500. At block 1804, at least one array of photosensitiveelements 163, is positioned within the chassis 310 in a position thatmakes the array of photosensitive elements 163 operable to receive lightfrom at least one array of light sources 450. At block 1806, at leastone opaque layer 240 is positioned to prevent light from propagatingfrom the arrays of light sources 450 to any one of the arrays ofphotosensitive elements 163. The opaque layer 240 is overlaid by thetransparent abrasive layer 275.

At block 1808, the alarm 500 is connected to communicate with the one ormore photosensitive elements correlated to the array of photosensitiveelements 163. The correlated photosensitive elements form the array ofphotosensitive elements 163. The arrays of photosensitive elements 163are electrically connected to the alarm 500 as indicated by arrow 175(FIG. 15).

At block 1810, the chassis 310 is closed when the at least one array oflight sources 450, the at least one array of photosensitive elements163, and the at least one opaque layer 240 are positioned within thechassis 310. At block 1812, the optical anti-tamper system 11 iscalibrated as described above with reference to block 1702 in method1700 of FIG. 17.

FIG. 19A is a top-view of an embodiment of the optical anti-tampersystem 15. The optical anti-tamper system 15 includes a light emittinglayer 600, a light detecting layer 700, light source 150, light detector160, and an alarm 500 enclosed within a chassis 310 and in contact witha proprietary part of component 45 that is to be protected from atampering event.

The light emitting layer 600 is optically coupled to the light source150. The light emitting layer 600 includes a plurality of emitteroptical fibers designated generally as 605. Emitter optical fibers 605are similar to emitter optical fibers 104 (FIG. 2) except that there areno bevel cuts in the emitter optical fibers 605. As shown in FIGS. 19Aand 19B, the input ends generally designated as 615 of the emitteroptical fibers 605 are bundled for optical coupling to one or more lightsources represented as a single light source 150. In this manner, one ormore light sources 150 are optically coupled to the light emitting layer600. The output ends generally designated as 617 of the emitter opticalfibers 605 are spatially separated by a distance that permits a detectoroptical fiber 706 to lie between adjacent emitter optical fibers 605.

A main body region generally designated as 607 of each of the emitteroptical fibers 605 lies in a straight line. The main body regions 607 ofneighboring emitter optical fibers 605 are separated by approximatelyequal distances. The main body region 607 ends at the output ends 617 ofthe emitter optical fiber 605. In one implementation of the embodimentof emitter optical fiber 605, the main body region 607 is about half thelength of the emitter optical fiber 605. In another implementation ofthe embodiment of emitter optical fibers105, the main body regions 607range from between half the length of the respective emitter opticalfiber 605 and three-quarters of the length of the respective emitteroptical fiber 605. The main body regions 607 of emitter optical fibers605 lie approximately in a plane defined by vectors X and Y.

The light detecting layer 700 is optically coupled to a light detector160. The light detecting layer 700 includes a plurality of detectoroptical fibers generally designated as 706. As shown in FIGS. 19A and19B, the output ends generally designated as 725 of the of detectoroptical fibers 706 are bundled for optical coupling to one or more lightdetectors represented as a single light detector 160. In this manner,one or more light detectors 160 are optically coupled to the lightdetecting layer 700 so that the light detector 160 is optically coupledto receive light that propagates through any of the detector opticalfibers 706. The input ends generally designated as 727 of the ofdetector optical fibers 706 are spatially separated by a distance thatpermits a emitter optical fiber 605 to lie between adjacent detectoroptical fibers 706.

A main body region 708 of each of the detector optical fibers 706 liesin a straight line. The main body regions 708 of neighboring detectoroptical fibers 706 are separated by approximately equal distances. Themain body region 708 ends at the input ends 727 of the detector opticalfiber 706. In one implementation of the embodiment of detector opticalfiber 706, the main body region 708 is about half the length of thedetector optical fiber 706. In another implementation of the embodimentof detector optical fiber 706, the main body region 708 ranges frombetween half the length of the respective detector optical fiber 706 andthree-quarters of the length of the respective detector optical fiber706.

The main body regions 708 of detector optical fibers 706 lieapproximately in the plane defined by vectors X and Y. Additionalphysical details of embodiments of the detector optical fibers 706 aredescribed below with reference to FIG. 3. In one implementation ofembodiments of light emitting layer 600 and light detecting layer 700,the distance between adjacent emitter optical fibers 605 is about 1.5 to3 times the diameter of the detector optical fibers 706 and the distancebetween adjacent detector optical fibers 706 is about 1.5 to 3 times thediameter of the emitter optical fibers 605. In another implementation ofembodiments of light emitting layer 600 and light detecting layer 700,the distance between all adjacent emitter optical fibers 605 anddetector optical fibers 706 is about equal.

The emitter optical fibers 605 of light emitting layer 600 areinterleaved with the detector optical fibers 706 of the light detectinglayer 700. The emitter optical fibers 605 and detector optical fibers706 can be glass optical fiber, plastic optical fibers, multimodeoptical fiber, single mode optical fiber, and any flexible light pipe.

The alarm 500 is operable as described above with reference to FIG. 7,to damage at least a portion of components 45 within the chassis 310responsive to a tamper-event warning signal so that the damaged portionof the components 45 are inoperable and/or irretrievable.

The optical anti-tamper system 15 operates to detect a tampering eventin which one or more of the emitter optical fibers 605 and one or moreof the detector optical fibers 706 are cut or broken. FIG. 19B is theoptical anti-tamper system of FIG. 19A in a broken state after at leasta portion of the light emitting layer 600 and the light detecting layer700 are cut as illustrated in cut area 401. FIG. 19C is an enlarged viewof the cut area 401. When an object cuts the interleaved light emittinglayer 600 and light detecting layer 700 as it overlies at least aportion of the component 45, a cutting-tampering event occurs. Light 302from light source 150 (FIG. 19B) that propagates along emitter opticalfiber 605A, 605B and 605C is emitted as light 130 from the cut ends610A, 610B and 610C, respectively (FIG. 19C). A portion of the light 130is optically coupled into detector optical fiber 706A and 706B at thecut ends 710A and 710B, respectively. The light coupled into the cutsends 710A and 710B of detector optical fibers 706A and 706B,respectively, propagates from the cut ends 710A and 710B to output ends725 and is coupled as light 300 into the light detector 160.

The detector 160 is in communication with alarm 500 as indicated byarrow 175 (FIG. 19B). The alarm 500 is operable to transmit atamper-event signal 360 to the external system 350 if an increased lightlevel is detected by detector 160. The external system 350 is externalto the chassis 310. The component 45 shown as one component in FIGS.19A-19B, is representative of one or more components. The portion of thecomponent 45 covered by the light emitting layer 600 and the lightdetecting layer 700 includes the proprietary technology. In this manner,the optical anti-tamper system 15 detects an increased light levelwithin the chassis responsive to cutting a light emitting layer 600located within a chassis and an adjacent a light detecting layer 700located within the chassis 310 generates tamper-event warning signalresponsive to the detecting and is enabled to damage at least a portionof components within the chassis 310 responsive to the generatedtamper-event warning signal.

Although specific embodiments have been illustrated and describedherein, it will be appreciated by those of skill in the art that anyarrangement, which is calculated to achieve the same purpose, may besubstituted for the specific embodiment shown. This application isintended to cover any adaptations or variations of the presentinvention. Therefore, it is manifestly intended that this invention belimited only by the claims and the equivalents thereof.

1. An optical anti-tamper system, the system comprising: at least onearray of light sources located within a chassis; at least one array ofphotosensitive elements located within the chassis, the array ofphotosensitive elements in communication with an alarm, wherein thealarm is operable to transmit a tamper-event warning signal if anincreased light level is detected by at least one array ofphotosensitive elements; an opaque layer located between the array oflight sources and the array of photosensitive elements, the opaque layeroperable to prevent light emitted from the array of light sources frombeing incident on the array of photosensitive elements when in anunbroken state; and a transparent layer located between the array oflight sources and the array of photosensitive elements, the transparentlayer operable to break the opaque layer when a protected componentpositioned adjacent to the transparent layer is touched during atampering event so that the opaque layer is in a broken state, whereinthe array of light sources and the array of photosensitive elements arepositioned so that the light emitted from the array of light sources isincident on the array of photosensitive elements when the opaque layeris in the broken state.
 2. The system of claim 1, wherein thetransparent layer comprises a gel and abrasive particles dispersedwithin the gel.
 3. The system of claim 1, wherein when light propagatesfrom the array of light sources to the array of photosensitive elementsthe resulting increased light detected by the array of photosensitiveelements initiates a tamper-event warning signal.
 4. The system of claim1, wherein an opaque-layer-break tampering event includes a relativemovement between two or more components within the chassis, wherein therelative movement causes the transparent layer to break the opaquelayer.
 5. The system of claim 4, wherein at least one of the two or morecomponents comprise an electronic circuit board.
 6. An opticalanti-tamper system, the system comprising: at least one array of lightsources located within a chassis; at least one array of photosensitiveelements located within the chassis, the array of photosensitiveelements in communication with an alarm, wherein the alarm is operableto transmit a tamper-event warning signal if an increased light level isdetected by at least one array of photosensitive elements, wherein thechassis in a closed state is impenetrable to light, wherein achassis-opening tampering event occurs when the chassis is open to anexternal environment and external ambient light reaches the array ofphotosensitive elements, and wherein the increased light level isdetected by the one or more arrays of photosensitive elements.
 7. Thesystem of claim 1, wherein the array of light sources is selected froman array of light emitting diodes, an array of lasers, an array ofvertical cavity light emitting diodes and combinations thereof, andwherein the array of photosensitive elements is selected from an arrayof photosensitive pixels, a charge-coupled device, an array ofphoto-detectors and combinations thereof.
 8. A method of manufacture,the method comprising: positioning at least one array of light sourceswithin a chassis; positioning at least one array of photosensitiveelements within the chassis operable to receive light from at least onearray of light sources; positioning at least one opaque layer to preventlight from propagating from the array of light sources to any one of thearrays of photosensitive elements; connecting an alarm in communicationwith one or more photosensitive elements correlated to the array ofphotosensitive elements; closing the chassis when the at least one arrayof light sources, the at least one array of photosensitive elements, andthe at least one opaque layer are positioned; and calibrating the atleast one array of photosensitive elements for an ambient light levelwithin a closed chassis.
 9. An optical anti-tamper system, the systemcomprising: means to break an opaque layer positioned over an array oflight sources responsive to a touching of one or more components withina chassis; means for detecting an increased light level at an array ofphotosensitive elements within the chassis responsive to the break; andmeans for generating a tamper-event warning signal responsive to thedetecting.
 10. The optical anti-tamper system of claim 9, the systemcomprising: means for damaging at least a portion of the componentwithin the chassis responsive to generating the tamper-event warningsignal, wherein the damaged portion of the component is made at leastone of inoperable and irretrievable.
 11. A method to detect a tamperingevent, the method comprising: breaking an opaque layer, wherein thebreak is located between an array of light sources and one or morearrays of photosensitive elements within the chassis; transmitting lightfrom a portion of the array of light sources through the opaque layerresponsive to breaking the opaque layer; detecting an increase in alight level at the one or more array of photosensitive elementsresponsive to the transmitting light; and generating a tamper-eventwarning signal responsive to the detecting.
 12. The method of claim 11,further comprising: damaging at least a portion of components within thechassis responsive to generating the tamper-event warning signal,wherein the damaged portion of the components is made at least one ofinoperable and irretrievable.
 13. The method of claim 12, furthercomprising: transmitting the tamper-event warning signal responsive togenerating the tamper-event warning signal.
 14. The method of claim 11,further comprising: transmitting the tamper-event warning signalresponsive to generating the tamper-event warning signal.
 15. The systemof claim 6, wherein the array of light sources is selected from an arrayof light emitting diodes, an array of lasers, an array of verticalcavity light emitting diodes and combinations thereof, and wherein thearray of photosensitive elements is selected from an array ofphotosensitive pixels, a charge-coupled device, an array ofphoto-detectors and combinations thereof.